175 Johnson back fires?????

[toocanshan]

i had just bought this motor and i replaced the # 1,3,5 coils and now the motor will start but back fires heavily. these are the #'s i got off the motor j175txcim and j5517850. if anyone could tell me what would cause a motor to back fire and if anyone knows what year motor this is that would be great. thanks to all!!!!! toocan

 

[jonesg]

Re: 175 Johnson back fires?????

is that a 1981?

try giving more background, you replaced the coils because...?
What is the basic problem?
How did you ascertain those coils had gone south, seems a coincidence.

Help the experts to help you.

 

[toocanshan]

Re: 175 Johnson back fires?????

the wires were broke on the coils when i got it so i took the ones off my other motor in replace. it fires right up runs a couple secs. and stalls out with a back fire.

 

[CharlieB]

Re: 175 Johnson back fires?????

You may have switched wires to the coils from the ignition module.

You need to double check the color codes in the factory manual, which color goes to which # coil.

You may figure it out by pulling plug wires at an idle, see which ones stop backfiring when pulled, then switch the primary lead from the module to the coils and retest.

 

[toocanshan]

Re: 175 Johnson back fires?????

the wires are perminently ran into each coil. the only ones that could be wrong is the top and bottom one should i swap the two??? and would this cause back fireing if they were wrong??

 

[Dhadley]

Re: 175 Johnson back fires?????

If it's backfiring out the exhaust (different than spitting back thru the carbs) then it's out of time. Since you just changed coils I'd look there. Check the primary wires to make sure they're in the right places. The plug leads should be very obvious. If the wires are right you may have flywheel key issues.

 

[emdsapmgr]

Re: 175 Johnson back fires?????

On that engine, when you replace a coil you have to reinstall the new orange coil wire and pin back into the original hole in the rubber plug which connects to the power pack. If you got the coil wire pin in the wrong hole in the plug, the pack may be trying to fire a coil/s at the wrong time, causing a backfire. The wires from the pack to the coils are color coded. On the power pack, the orange wire with the blue tracer should be connected through the plug to the top coil on that side. The orange only wire from the pack fires the middle coil and the orange wire with green tracer fires the bottom coil.

 

[jriegle04]

Re: 175 Johnson back fires?????

your motor is a 1981. http://www.maxrules.com/OMC_models_files/1980_1999/175_300.html i would check my flywheel magnets for loose or broken pieces if i were you. i have a 1985 150 hp that had similar issues and it was as simple as removing the flywheel and JB welding a magnet back into place. it is free and easy to check. let us know what you find